Calculating heat generated by a resistance wire

How can I calculate how much heat a resistance wire gives off when I energize it? For example, I have calculated the wattage per square inch of a heating element I plan on building. How do I know how much actual heat it will give off?

The medium is air. I am basically trying to design my own infrared heating panel to heat an epoxy to 350F. I am not concerned about losses as I plan on over compensating with temperature i.e. designing a coil that will go to 600F or so. Basically i need to figure out how to calculate how much heat a coil has the ability to "give off". To go into more detail, I want to design a 16"x16" heating panel that has the ability to heat epoxy about 5" away to 350F. I plan on using a resistive heating wire and making my own coil. This should save me about $600 :OP

*I plan on using a nickel-chromium wire of lengh and resistance to be determined.